caret train method not working (something is wrong for all accuracy results) for outcomes with >2 categories

Question

Hi I know someone asked similar issues before but no clear answer yet (or I tried their solution without success: Caret error using GBM, but not without caret Caret train method

Answer 1

You need to convert the newly created Class_new to a factor, as follows:

Sonar$Class_new<-ifelse(Sonar$Class=="R","R",ifelse(Sonar$rand>0,"M","H"))
Sonar$Class_new <- factor(Sonar$Class_new)

Also, you may want to remove the variables Class and rand from your training and testing data sets. You can do somthing like:

training <- Sonar[ inTraining, !(names(Sonar) %in% c("Class", "rand"))]
testing <- Sonar[-inTraining, !(names(Sonar) %in% c("Class", "rand"))]